The present invention relates to an elastic body, a method for manufacturing the same, and a mattress including the same, and more particularly to an elastic body having suitable elasticity and capable of retaining various additives for a long period of time, an advantageous method for manufacturing the same and a mattress including the same, thereby providing suitable elasticity and comfort for users.
Generally, iron coil springs, highly dense sponge blocks made from polyurethane or latex, or rubber balls have been used as elastic supporting means for bed mattresses.
The iron coil springs have been the most widely used elastic supporting means for the bed mattresses because they can provide superior elasticity for a long period of time. There are, however, some drawbacks to the iron coil springs for users. Since a plurality of springs are used by being connected to one another, pressure or impact applied to a particular area of a mattress causes the entire mattress to shake, thereby providing an unstable feel to the users. In addition, metallic noise disturbs the users, and sometimes the springs pierce the upper portion of the mattress to the extent that a mattress cover or sheet is damaged.
Bed mattresses using the highly dense sponge blocks made from polyurethane or latex do not generate such metallic noise, but allow the users to have comfortable sleep with a soft feel. However, the elasticity of the sponge blocks not only reduces as time passes, but also becomes uneven as a rebound property of the sponge blocks at the most used portions of a mattress such as edges is relatively lowered.
The rubber balls having a single inner space or air balls having a plurality of separated inner spaces are elastic supporting means that can provide a comfortable feel different from the feel of the above-mentioned springs or sponge blocks. The elasticity of such balls decreases whenever air is leaked out of the balls as time passes, and it becomes uneven due to climate influence. To fill the air-leaked balls with air or to exchange them to new balls is not only a hassle but also an expense. Moreover, a peculiar rubber smell from aging ruins a comfortable indoor environment.
In order to solve the aforementioned problems found in each elastic supporting means, the present inventor disclosed an elastic and independent body as Korean utility model number 0135979, filed on Aug. 9, 1996 and issued on Nov. 9, 1998. The elastic and independent body is an air permeable sponge having a net-shaped structure with air holes and sponge membranes made from polyurethane- and rubber-based compounds.
In comparison with prior elastic supporting means, the elastic and independent body provides superior comfort for its users on the grounds that its elasticity is uniformly maintained regardless of the lapse of time or changes in weather conditions, that it is free from a smell from aging, and that it provides suitable elasticity and softness. In the said Korean utility model, a mattress is manufactured in such a way that a plurality of independently formed elastic bodies are arranged to form a mattress shape and are supported and wrapped. This mattress is designed to minimize a transmission of fluctuation caused by a person lying on a certain mattress surface to an extent that the next person lying on the mattress is not affected.
FIG. 1A is a perspective view of an air permeable sponge elastic body and FIG. 1B is a cross-sectional view showing the inner structure of the air permeable sponge elastic body.
Referring to FIG. 1A, an air permeable sponge elastic body 10 has a substantially cylindrical shape, and its center portion has a concave portion 14 to which two convex portions 12, 13 are adjacent. Each of the two convex portions 12, 13 in a spherical shape is truncated in an upper portion 16 and in a lower portion 17, respectively. The elastic body 10 has superior elasticity arising from its material and structural properties. The elastic body 10 having the concave portion 14 at the center thereof as shown in FIG. 1A can provide its users with comfort in harmony with elasticity and resilience.
Since this elastic body has an elasticity stemmed from a foamed membrane, an absorption force of an external impact is weak whereas a repulsive force thereof is strong. Each foam, making contact with its adjacent foams, in the net-shaped sponge structure is air permeable. Due to the air permeability, there is a problem that additives such as anti-bacteria agents and perfumes are easily volatilized into the air via passages, so that-effects provided by the additives are reduced by the use for a long period of time.
Referring to FIG. 1B, the inner structure of the elastic body 10 is shown with an enlarged cross-sectional view. The inner structure has a plurality of foams 16 which are air permeable, so that air can pass among and through the adjacent foams. It should be noted that although each foam is merely illustrated in a spherical shape for convenience, the foam could be formed in various shapes in practice to have a predetermined space.
Therefore, taking account of the above problems, it is a first object of the present invention to provide an elastic body capable of maintaining a proper elasticity for a long-term use and retaining additives such as anti-bacterial agents and perfumes for a long period of time.
It is a second object of the present invention to provide an advantageous method of manufacturing the elastic body.
It is a third object of the present invention to provide a mattress which is manufactured by using the elastic body, so that it has a good elasticity and an improved impact absorption force.
To achieve the first object, there is provided an elastic body which is made from a foamed polyurethane polymer including polystyrene and has a plurality of foams in which air is contained and at least one concave portion at the center thereof. The elastic body is prepared by a method comprising the steps of mixing a polyol compound and a polyether compound in a mixing ratio of 3-5 to 5-7 by weight, adding 2-20 parts by weight of polystyrene and a trace amount of a catalyst to 30-50 parts by weight of the obtained mixture, adding and stirring 20-60 parts by weight of an isocyanate compound and water at 20-80xc2x0 C., and molding the obtained reactant.
The second object of the present invention is accomplished by a method comprising the steps of obtaining polyether polyol by mixing poly alcohol and a polyether compound in a mixing ratio of 3-5 to 5-7 by weight, producing a polyol mixture by adding 2-20 parts by weight of polystyrene, a trace amount of a catalyst and water to 30-50 parts by weight of the obtained polyether polyol, and mixing 40-80 parts by weight of the obtained polyol mixture and 20-60 parts by weight of an isocyanate compound at 20-80xc2x0 C. and foam molding the obtained reactant.
The third object of the present invention is accomplished by a mattress comprising an elastic body array obtained by arranging side by side the above mentioned elastic bodies within a predetermined area, a supporter which is assembled to support said elastic bodies at concave portions of said elastic bodies, two flat plates provided at upper and lower portions of said elastic body array, and a wrapping means for wrapping said elastic body array, said supporter and said flat plates.